A silica glass crucible is used for pulling a single-crystal silicon which is a material of a semiconductor device or a crystal silicon which is a material of a solar cell. For example, the single-crystal silicon is mainly produced by heating and melting polycrystalline silicon nuggets charged into a silica glass crucible to obtain silicon melt, dipping a seed crystal into the silicon melt, and pulling the seed crystal upwards. The silicon crystal which is the material of the solar cell is also produced by the same growing method.
The silica glass crucible is produced by a rotation mold method or the like. According to this method, silica powder of a predetermined thickness is deposited on an inner surface of a crucible-like rotation mold, and the silica powder layer is heated and melted while rotating the mold, thereby glassifying the silica powder layer to produce a crucible (Japanese Patent Applications Laid-open Nos. S56-17996 and S56-149333). There is also a known method in which silica powder partially melted is cause to adhere to an inner surface of a rotation mold to produce a silica glass crucible (Japanese Patent Application Laid-open No. H01-148718).
When a produced silica glass crucible is to be taken out of the mold in conventional methods, the mold is turned upside down to take the crucible out, the mold is laid down sideways to pull out the crucible, or the crucible is pulled out using a suction cup. According to such methods, however, a risk that the crucible is damaged is high. Further, because a large amount of non-melted silica powder adheres to an outer surface of the crucible, there is a risk that the silica powder adheres to an inner surface of the crucible and damages the inner surface. The silica glass crucible is easily damaged if it is subjected to impact. Therefore, a device which mechanically grasps a crucible or a mold to take the crucible out of the mold has a high risk. Therefore, delicate adjustment of a force is required, and thus great reliance has been placed upon manual operations. However, in recent years, the crucible is increased in size, and mechanical automation which does not rely on manual operations is demanded.